Narrow border has become more popular in panel design nowadays; the narrow border products also have stronger competitiveness in the market.
In a TFT-LCD panel of a vertical alignment (VA) type, a color filter (CF) is important for the formation of the liquid crystal capacitor, and the control of the deflection of the liquid crystal molecules. Because the IC for controlling the color filter is mounted to a TFT substrate, a transfer pad which can transfer a signal of a common electrode of the CF from the TFT substrate to the CF substrate is a necessary structure for the display panel of a VA type. Usually, the common electrode signal of the CF is transferred to the CF substrate through Au balls at a transfer position; a size of the transfer pad is often larger than usual, occupying more peripheral wiring space, which is very bad for the existing narrow border design. In order to decrease the size of the transfer pad, an Au-in-seal method is often used, that is, the Au balls are distributed in the frame seal, which is evenly coated on the peripheral position of the panel. Thus the signal of the common electrode of the CF is transferred to the CF substrate through a smaller transfer pad. A drawback of this approach is that conductive materials contained at the seal are only allowed to electrically connect with the common electrode for the CF, and not allowed to contact any via (contact hole) of other signals; otherwise short circuits happen in different signals, and the panel can not work normally. The problem is more serious in gate driver on array circuits (GOA). This is because of the many frequency signal lines on the gate side of the GOA circuit. The frequency signal lines usually overlap with the seal frame, and the frequency signal lines have many vias through which the frequency signal lines connect with the GOA circuit. The Au-in-seal technology used in the narrow border panel results in the problem of a short circuit of the frequency signal in the GOA circuit.
FIG. 1 is a diagram of peripheral wiring on the gate side of the panel of a traditional GOA circuit. For a panel using a GOA structure, the amount of frequency signals used by the GOA circuit, such as CK1, CK2 in FIG. 1, is more, occupying more space on the gate side. The frequency signal needs the vias (contact holes) 10 to be transferred to the GOA circuit. If these vias 10 contact with the Au balls (not shown), then a short circuit thus happens between different signals, which makes the GOA circuit not able to work normally.
FIG. 2 illustrates a cross-sectional view of the frequency signal line in FIG. 1. As shown in FIG. 2, the GOA circuit 2 is often made of a first metal layer 20, conducted to a frequency line formed by a second metal layer 21 through the via 10. At the via 10, a dielectric layer on the metal line is dug through dry etching. An Indium Tin Oxide (ITO) electrode 22 is formed to connect the metal lines of different layers. A voltage level of the frequency signal is on the ITO electrode 22, if directly contacting with the Au ball (not shown) at a seal, the short circuit of the frequency signal and the signal of the common electrode of CF happens, which makes the GOA circuit not able to work normally.